Epidermal cell growth factors receptors (EGFR) are identified as one significant driving factor in the process for cellular growth and proliferation. The epidermal cell growth factors receptors family is composed of EGFR (Erb-B1), Erb-B2 (HER-2/neu), Erb-B3 and Erb-B4. The epidermal cell growth factor receptors are associated with the process for most cancers, such as lung cancer, colon cancer, breast cancer and the like. The overexpression and mutation of EGFR have been proved to be the leading risk factor for a breast cancer with poor prognosis.
The current edge-cutting research is focused on an irreversible third-generation EGFR inhibitor. The patent application CN201410365911.4 discloses the following compound of formula (I), which compound has a substantially higher inhibition activity to the EGFR activating mutation (such as exon 19 deletion activating mutation, or L858R activating mutation) and T790M resistance mutation than the inhibition activity to the wild-type EGFR (WT EGFR), with a good selectivity, a relatively low toxicity side-effect and a good safety.

A crystalline form has some influence on the physical properties of the compounds. Due to the different crystal lattice structures, a pharmaceutical compounds showing polymorphs may have not only different appearances such as color and shape, but also different physical properties such as melting point, solubility, density, stability, hygroscopicity and the like, resulting in that they show different dissolution and absorption behaviors in vivo. This might have influence on the clinically therapeutical effect and safety of the pharmaceutical compounds to a certain extent.
Specific crystalline form will have a different thermodynamic behavior as compared to amorphous or another crystalline form. Melting point apparatus, thermogravimetric analysis (TGA) or differential scanning calorimetry (DSC) or the like can be used in laboratories to measure the thermal properties, to differentiate a certain specific crystalline form from an amorphous and another crystalline form. Specific crystalline forms may have special spectral properties. For example, the data of both X-ray powder diffraction pattern and IR spectra can characterize specific crystalline forms.